Nixon authorizes invasion of Cambodia, April 28, 1970

On this day in 1970, President Richard Nixon authorized U.S. combat troops to cross the border from South Vietnam into Cambodia. The preemptive strike was aimed at forestalling communist North Vietnamese attacks into South Vietnam from their sanctuaries there even as the South Vietnamese were being primed to assume more responsibility for the conduct of the war and U.S. forces were being withdrawn.

Both Secretary of State William Rogers and Defense Secretary Melvin Laird were kept in the dark about Nixon’s decision until it was made public two days later. Three top staff members of the National Security Council, headed by Henry Kissinger, resigned in protest.

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On April 30, in a 2,700-word televised address to the nation, Nixon sought to justify his decision as a required response to North Vietnamese aggression. His speech triggered a fresh wave of antiwar demonstrations, which led to the killing of four students at Kent State University when Ohio National Guard troops fired on protesters.

On April 25, Nixon had dined with Kissinger and with his friend Bebe Rebozo. Afterward, they watched “Patton,” a film about Army Gen. George Patton. It was the sixth time Nixon had watched the movie. Kissinger later said that “when [Nixon] was pressed to the wall, his romantic streak surfaced and he would see himself as a beleaguered military commander in the tradition of Patton.”

All in all, the Army of the Republic of Vietnam conducted 13 major operations from April 29 to July 22. U.S. combat forces joined in these actions from May 1 to June 30.

The Cambodian incursion angered many members of Congress who accused Nixon of having widened the war illegally. Still, it took five more years and a communist takeover of South Vietnam for American forces to fully depart.